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低蛋白日粮 1

假单胞菌 1

富含异亮氨酸的延伸蛋白 1

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Insulin resistance and the metabolism of branched-chain amino acids

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《医学前沿（英文）》 2013年第7卷第1期页码 53-59 doi: 10.1007/s11684-013-0255-5

摘要：

Insulin resistance (IR) is a key pathological feature of metabolic syndrome and subsequently causes serious health problems with an increased risk of several common metabolic disorders. IR related metabolic disturbance is not restricted to carbohydrates but impacts global metabolic network. Branched-chain amino acids (BCAAs), namely valine, leucine and isoleucine, are among the nine essential amino acids, accounting for 35% of the essential amino acids in muscle proteins and 40% of the preformed amino acids required by mammals. The BCAAs are particularly responsive to the inhibitory insulin action on amino acid release by skeletal muscle and their metabolism is profoundly altered in insulin resistant conditions and/or insulin deficiency. Although increased circulating BCAA concentration in insulin resistant conditions has been noted for many years and BCAAs have been reported to be involved in the regulation of glucose homeostasis and body weight, it is only recently that BCAAs are found to be closely associated with IR. This review will focus on the recent findings on BCAAs from both epidemic and mechanistic studies.

关键词： branched-chain amino acids leucine isoleucine valine insulin resistance

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Regulation of NLR stability in plant immunity

Tao WANG, Jiaxin LI, Qian-Hua SHEN

《农业科学与工程前沿（英文）》 2019年第6卷第2期页码 97-104 doi: 10.15302/J-FASE-2018248

摘要：

Plant nucleotide binding domain and leucine-rich repeat (NLR) receptors recognize pathogen effectors directly or indirectly and mediate innate immune responses. NLR-mediated immunity also has direct impacts on plant growth and development, as well as yield and survival. The levels of NLR proteins are therefore intricately controlled in plants to balance defense responses and other processes. In recent years, the ubiquitination-26S proteasome system and the HSP90 chaperones have emerged as having key functions in the regulation of NLR stability. The N-end rule pathway of protein degradation is also directly linked to NLR stability. Recent progress in the regulation of NLR stability and turnover is summarized here, focusing on the key components and pathways.

关键词： E3 ubiquitin ligase degradation nucleotide-binding leucine-rich repeat receptor plant immunity proteasome protein stability ubiquitination

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低蛋白日粮中添加亮氨酸通过雷帕霉素靶蛋白信号通路增加成年大鼠骨骼肌重量及蛋白质合成

张博, 楚丽翠, 刘宏, 谢春元, 谯仕彦, 曾祥芳

《工程（英文）》 2017年第3卷第5期页码 760-765 doi: 10.1016/J.ENG.2017.03.008

摘要：

低蛋白日粮会减少动物组织中蛋白质沉积，影响骨骼肌增重。本文旨在研究低蛋白日粮中添加亮氨酸对成年大鼠骨骼肌重量和蛋白质合成的影响。试验选取36只平均体重为（214.4 ± 2.4）g的成年SD雄性大鼠，按体重相近原则平均分为3个处理，每个处理12个重复，每个重复1只大鼠。3个处理分别饲喂20%酪蛋白（20%C，CON）、10%酪蛋白 + 丙氨酸（10%C + Ala，R）以及10%酪蛋白 + 亮氨酸（10%C + Leu，RL）日粮，试验期为11 d，其中，10%C + Ala组和10%C + Leu组为等氮日粮组。试验第11天，所有大鼠大剂量一次性腹腔注射L-[ring-2H5]苯丙氨酸注射液，测定血清中的氨基酸含量、比目鱼肌和腓肠肌重量、蛋白质合成速率及mTOR信号通路相关分子的表达。结果表明，在3个处理中，RL组血清亮氨酸含量最高（P < 0.05），而异亮氨酸含量最低（P < 0.05）；CON组的缬氨酸含量低于R和RL组（P < 0.05），但采食量、蛋白质合成速度和4EBP1的磷酸化高于R和RL组（P < 0.05），同时腹脂重量显著下降（P < 0.05）。与R组相比，RL组可以增加腓肠肌重量（P < 0.05），促进S6K1磷酸化（P < 0.05），增加骨骼肌蛋白质合成（P < 0.05）。本文结论如下，在成年大鼠长期采食低蛋白日粮的情况下，日粮中添加亮氨酸可以改善大鼠的生长性能，通过提高mTOR通路中S6K1磷酸化水平，促进大鼠骨骼肌蛋白质合成，抑制蛋白质降解。

关键词：低蛋白日粮亮氨酸生长性能肌肉重量蛋白质合成成年大鼠

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Synthesis of depsipeptides from

Hongfei CAO, Yakai FENG, Heyun WANG, Li ZHANG, Musammir KHAN, Jintang GUO

《化学科学与工程前沿（英文）》 2011年第5卷第4期页码 409-415 doi: 10.1007/s11705-011-1141-9

摘要： By using the corresponding -amino acid sodium as initiator, -caprolactone-depsipeptides CL-Ala and CL-Leu were prepared by the reactions of -caprolactone (CL) with -alanine and -leucine, respectively, and -dioxanone-depsipeptide (PDO-Leu) was prepared by the reaction of -dioxanone (PDO) with -leucine. Two poly( -caprolactone) oligomers (PCL-Ala and PCL-Leu) of different molecular weights with depsipeptide unit were synthesized by controlling the feed ratio of -amino acid sodium and CL. The presence of the depsipeptide structure in these obtained products was confirmed by H NMR spectra and the molecular weight of the poly( -caprolactone) oligomers was measured by gel permeation chromatography (GPC). These products contain a hydroxyl group and a carboxyl group in one molecule, which means they could act as bifunctional monomers for further polymerization to prepare high molecular weight polymers. By this way, the depsipeptide unit could be introduced into the polymers and the biodegradation rates of the novel polymers could be well controlled in vivo by the tailored molecular structures.

关键词： ?-caprolactone p-dioxanone L-alanine L-leucine depsipeptide

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假单胞菌环状脂肽Medpeptin的生物合成及其调控植物免疫的作用机制 Article

谷医林, 李俊州, 李彦, 从珅, 王静, 马毅楠, 魏海雷

《工程（英文）》 2023年第28卷第9期页码 153-165 doi: 10.1016/j.eng.2023.05.016

摘要：

环状脂肽（cyclic lipopeptides, CLP）是一类由细菌产生的多功能次生代谢产物，也是一类重要的植物免疫激发子。假单胞菌环状脂肽在结构和生物活性上极其复杂和多样化。但是，目前对环状脂肽的结构及其与植物互作中的功能认识仍比较有限。本研究从地中海假单胞菌中鉴定了一种由22个氨基酸组成的新型的环状脂肽medpeptin，该脂肽由一个非核糖体肽合成酶基因簇合成并受群体感应系统调节。进一步研究发现，medpeptin可以诱导植物产生免疫反应，增强植物对病原细菌的抗性，但其自身不具备抗菌活性。利用比较转录组分析和病毒诱导的基因沉默技术解析了参与medpeptin感知植物免疫信号候选关键基因。结果显示，当沉默本氏烟中细胞壁富含亮氨酸的重复延伸蛋白NbLRX3或类受体蛋白激酶NbRLK25后，medpepatin触发的细胞死亡和对病原细菌的抗性受到严重影响，而沉默BAK1或SGT1则并未影响这一表型。本研究结果揭示了一种非典型的CLP感知机制，并为植物抗病免疫研究提供了新的借鉴。

关键词：假单胞菌环状脂肽细胞死亡富含异亮氨酸的延伸蛋白类受体激酶